This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A360915 #11 Feb 16 2025 08:34:04 %S A360915 4,4,4,4,8,4,4,10,10,4,4,12,12,12,4,4,14,14,14,14,4,4,16,16,16,16,16, %T A360915 4,4,18,20,18,18,20,18,4,4,20,22,24,20,24,22,20,4,4,22,24,26,28,28,26, %U A360915 24,22,4,4,24,28,28,30,32,30,28,28,24,4,4,26,30,32,32,36,36,32,32,30,26,4 %N A360915 Array read by antidiagonals: T(m,n) is the length of the longest induced cycle in the grid graph P_m X P_n. %C A360915 All terms are even since the grid graph is bipartite. %H A360915 Nikolai Beluhov, <a href="https://arxiv.org/abs/2301.01152">Snake paths in king and knight graphs</a>, arXiv:2301.01152 [math.CO], 2023. %H A360915 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/GridGraph.html">Grid Graph</a>. %F A360915 T(m,n) = T(n,m). %F A360915 T(m,n) = 2*m*n/3 + O(m+n) (Beluhov 2023, Proposition 3). - _Pontus von Brömssen_, May 08 2023 %e A360915 Array begins: %e A360915 ========================================== %e A360915 m\n| 2 3 4 5 6 7 8 9 10 11 12 ... %e A360915 -----+------------------------------------ %e A360915 2 | 4 4 4 4 4 4 4 4 4 4 4 ... %e A360915 3 | 4 8 10 12 14 16 18 20 22 24 26 ... %e A360915 4 | 4 10 12 14 16 20 22 24 28 30 32 ... %e A360915 5 | 4 12 14 16 18 24 26 28 32 36 38 ... %e A360915 6 | 4 14 16 18 20 28 30 32 36 42 44 ... %e A360915 7 | 4 16 20 24 28 32 36 40 44 48 52 ... %e A360915 8 | 4 18 22 26 30 36 40 46 50 56 60 ... %e A360915 9 | 4 20 24 28 32 40 46 50 56 62 68 ... %e A360915 10 | 4 22 28 32 36 44 50 56 62 70 74 ... %e A360915 11 | 4 24 30 36 42 48 56 62 70 76 82 ... %e A360915 12 | 4 26 32 38 44 52 60 68 74 82 90 ... %e A360915 ... %Y A360915 Main diagonal is A357357. %Y A360915 Cf. A360196, A360913, A360917, A360920. %K A360915 nonn,tabl %O A360915 2,1 %A A360915 _Andrew Howroyd_, Feb 26 2023